As we noted late last month, the iAd rollout is slower than many had anticipated. Of the 17 launch partners Apple announced in July, only 6 have launched campaigns, including Nissan, Unilever, Citigroup, Disney, and JC Penney.

What's slowing everything down? In part, Apple's control over iAds: Apple is making the ad creative themselves (which is probably part of why it looks so good). It hasn't released a SDK yet for advertisers to make their own ads. And it doesn't tell them where their ads are showing.

One ad agency exec, who isn't involved in any iAds, slammed the effort: "It's a huge issue having Apple in the creative mix," said Patrick Moorhead, director of mobile platforms at DraftFCB.

At least company announced at Apple's iAd launch, Chanel, seems to have pulled out, and "doesn't have a campaign planned at this time," the WSJ notes.

One iPhone app developer -- Loopt CEO Sam Altman, simultaneously complimented and took a whack at the iAd's slow rollout: "I think it's the best looking ad format and will perform long term, but the start has been disappointingly slow," he told the WSJ. (Altman has appeared on stage at an Apple event and has received free promotion from Apple, so if he's frustrated, many developers could be frustrated.)

Apple "underestimated how tough the new business would be and is still learning the best tactics for dealing with ad agencies," the WSJ writes.

The WSJ also confirmed that the cheaper "iAd for Developers" ads, which let iPhone developers promote their apps within other apps, cost 25 cents per click, which we first reported last month.

After a quick burst of launch activity, some developers tell us they're surprised how slowly the iAd rollout is going; that they only see the two companies' iAds running; and that fill rates hover in the single-digits to around 10%.

But it appears (and makes sense) that Apple is actually rolling out iAd slowly on purpose, to make sure it doesn't unleash a monster before it's happy with the way everything works.

After asking Apple when more iAd campaigns would roll out, one developer tells us that Apple said, "We will ramp up the number of ads served in the weeks and months ahead."

Important to note: Besides the deliberately slow rollout, it's also a slow advertising period.

We'll be able to really judge the iAd program -- for developers relying on it for ad income, and for Apple's prospects in the mobile ad industry -- closer to the holidays.